Send Orders for Reprints to [email protected] 378 The Open Orthopaedics Journal, 2013, 7, 378-384 Open Access Hyaluronic Acid (HA) Viscosupplementation on Synovial Fluid Inflammation in Knee Osteoarthritis: A Pilot Study Heather K. Vincent*,1, Susan S. Percival2, Bryan P. Conrad1, Amanda N. Seay1, Cindy Montero1 and 1 Kevin R. Vincent 1Department of Orthopaedics and Rehabilitation, Interdisciplinary Center for Musculoskeletal Training and Research, 2Department of Food Sciences and Nutrition, University of Florida, Gainesville, FL 32608, USA Abstract: Objective: This study examined the changes in synovial fluid levels of cytokines, oxidative stress and viscosity six months after intraarticular hyaluronic acid (HA) treatment in adults and elderly adults with knee osteoarthritis (OA). Design: This was a prospective, repeated-measures study design in which patients with knee OA were administered 1% sodium hyaluronate. Patients (N=28) were stratified by age (adults, 50-64 years and elderly adults, 65 years). Ambulatory knee pain values and self-reported physical activity were collected at baseline and month six. Materials and Methods: Knee synovial fluid aspirates were collected at baseline and at six months. Fluid samples were analyzed for pro-inflammatory cytokines (interleukins 1, 6,8,12, tumor necrosis factor-, monocyte chemotactic protein), anti-inflammatory cytokines (interleukins 4, 10 13), oxidative stress (4-hydroxynonenal) and viscosity at two different physiological shear speeds 2.5Hz and 5Hz. Results: HA improved ambulatory knee pain in adults and elderly groups by month six, but adults reported less knee pain- related interference with participation in exercise than elderly adults. A greater reduction in TNF- occurred in adults compared to elderly adults (-95.8% ± 7.1% vs 19.2% ± 83.8%, respectively; p=.044). Fluid tended to improve at both shear speeds in adults compared to the elderly adults. The reduction in pain severity correlated with the change in IL-1 levels by month six (r= -.566; p=.044). Conclusion: Reduction of knee pain might be due to improvements in synovial fluid viscosity and inflammation. Cartilage preservation may be dependent on how cytokine, oxidative stress profiles and viscosity change over time. Keywords: Cytokine, inflammation, knee, osteoarthritis, pain, viscosity. INTRODUCTION pro-oxidant processes that result in oxidative modification of molecules. Relevant to osteoarthritis, byproducts of lipid Knee osteoarthritis (OA) may be triggered by excessive oxidation such as 4-hydroxynonenal (4-HNE) induce cell joint forces, defects to the articular cartilage or subchondral damage and death of chondrocytes [4, 5]. An imbalance of bone. Chondrocytes become metabolically active and initiate antioxidant defenses relative to oxidative processes has been inflammatory processes that degrade articular cartilage and shown to exist in human OA [3, 6]. The levels of oxidatively subchondral bone. Chondrocytes secrete several damaged byproducts such as lipid peroxides, are high in inflammatory cytokines that work synergistically to synovial fluid in patients with OA [3, 6]. These adverse stimulate synthesis of enzymes that break down cartilage. changes correspond with cartilage breakdown. Key cytokines include interleukin-1 (IL-1), tumor necrosis factor (TNF-) and interleukin-6 (IL-6) [1]. IL-1 and TNF- Normally, synovial fluid contains high levels of are commonly increased in inflamed joints, and these hyaluronic acid (HA) that help to maintain high fluid cytokines activate other inflammatory chemokines such as viscosity and the normal integrity of the joint by attenuating monocyte chemotactic proteins and others [2]. Hence, inflammation and preserving the normal cartilaginous inflammation is a critical modifier of joint disease and matrix. In OA, the synovial fluid viscosity and elasticity are progression. decreased [7, 8]. HA is a polysaccharide produced by the chondrocytes and synoviocytes. While HA may help to Intriguing, but very limited evidence also suggests a role lubricate and cushion the joint [9], it can help maintain for oxidative stress-related degradation processes in human cartilage matrix and minimize inflammation. In OA, the OA [3]. Oxidative stress represents the imbalance between molecular weight and concentration of HA are reduced [10], endogenous antioxidant defenses and the free radical induced thereby lowering fluid viscosity and elasticity. Protection against articular injury is compromised and OA damage *Address correspondence to this author at the Department of Orthopedics ensues. In vitro data suggest supplemental HA can suppress and Rehabilitation, Division of Research, UF Orthopaedics and Sports IL-1 production [11], and may increase synovial fluid Medicine Institute, PO Box 112727, Gainesville, FL 32611, USA; Tel: viscosity [10]. We hypothesize that intraarticular HA can (352) 273-7459; Fax: (352)-273-7388; E-mail: [email protected] suppress not only IL-1, but also can reduce the overall 1874-3250/13 2013 Bentham Open Synovial Fluid Changes with Hyaluronic Acid The Open Orthopaedics Journal, 2013, Volume 7 379 inflammatory cytokine response in human OA. Clinical to the Kellgren–Lawrence (KL) radiographic rating scale practice and anecdotal evidence suggest that HA may be [18] by the study physician (KRV). All patients read, more beneficial in mild to moderate OA [12]. However, understood and signed a UF IRB approved informed consent most of evidence on disease severity and age has been form. The selection of 28 participants was based on the derived from animal models of OA [13, 14]. Human studies ability to detect a minimal clinically relevant reduction in have found that patients>60 years with higher disease knee pain severity of 30% by month six [19], and a ~50% severity responded better to HA than counterparts younger decrease in IL-1 similar to that observed in HA injection in than 60 years [15]. Identification of the patient type with other articular joints [20]. better responsiveness to HA would be an important next step in optimizing OA treatment for this clinical population. Patient History and Physical Activity Patterns Although published data on this topic are limited, we All patients completed a specific health history surmise that HA may be important in suppressing oxidative questionnaire which included demographic data, current and stress by reducing toxic oxidative byproducts [16] such as 4- past medical issues, current medications, knee OA history HNE in the synovium. This suppression might be related to and current medications. The current physical activity improvements in knee pain symptoms, improvements in patterns were captured by documenting the type of exercise, physical activity and synovial fluid viscosity. These issues the number of weekly activity sessions, and the average remain unclear at the present time. Therefore, the primary session duration in block levels. The duration block levels purpose of this study was to compare the six month changes were: 1) 10-15 min, 2) 15-30 min, 3) 30-45 min, 4) 45min-1 in synovial fluid cytokine levels, 4-HNE and fluid viscosity hr and 5) 1 hour. For example, a participant who walked after an intraarticular HA injection series in adults and three times a week for 45 minutes would have the exercise elderly adults with knee OA. The secondary purpose was to pattern entered into the statistical program as: walking determine whether there were improvements in knee pain (activity type), 3 (frequency per week), block 3 (duration of and physical activity levels. This information will enhance walking). Knee pain severity was self-assessed during our understanding of the mechanisms of joint repair and walking activity using an 11 point numerical pain rating functional outcomes with intraarticular HA. scale (NRSpain) with terminal anchors (0 = “no pain”; 10 = “worst possible pain”). The NRSpain is an accepted outcome MATERIALS AND METHODOLOGY measure for chronic pain conditions, as described in the Initiative on Methods, Measurement, and Pain Assessment in Study Design Clinical Trials [21]. This measurement is reliable and valid This was a prospective, repeated-measures study design [22] for assessing pain intensity. in which the effects of a HA viscosupplement injection series on inflammatory parameters and viscosity of knee Intraarticular Injection Procedure for Hyaluronic Acid synovial fluid aspirates were examined. Pre-injection and The patient sat with the knee(s) flexed at 90º. The month six levels of synovial fluid biomarker levels injection site was cleansed with chlorhexidine, and local (inflammatory, oxidative stress) and fluid viscosity were anesthesia was provided to the pathway for the injection measured. This study was approved by the University of using three mL of 1% lidocaine. An anteromedial or lateral Florida Institutional Review Board (UFIRB), and all approach was performed for these injections. A 20g needle procedures on human subjects were conducted in accordance with a 20 ml syringe was utilized to withdraw synovial fluid with the Helsinki Declaration of 1975, as revised in 2000. aspirate to be used for subsequent analysis. The aspirate was All patients read, understood and signed an informed consent immediately aliquoted and frozen at -70°C. A preloaded document. syringe of two ml of viscosupplement (Euflexxa®.) was then delivered through a 20-gauge 1 inch needle using the Patients anteromedial or lateral approach. The patients were observed Patients (N=28) with chronic knee OA were